After some looking and measuring came across this the bearing seat is a little too big.
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Thank you for finding this. That’s definitely out of spec - can’t believe I didn’t notice it on any of the ones I disassembled.
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That is a little wider than it should be, but it shouldn’t be cutting strings. Thats a radiusing issue.
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Anyone have some nylons, not the string, the undergarment, to spare (I don’t sadly) but rubbing nylons over the surface will reveal the snags, trick from guitar set up
Might be helpful in finding what the exact problem is
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The one time I start assuming someone’s talking about string, and I get fooled! 
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This is HosieryExpert Forums after-all 
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My red one does this, not not quite as badly as yours. The bearing seat gap in my red one is visually bigger than on the other ones.
Of the 1 A grade and 3 B grades I got, only one has this issue. It’s not all of them.
Here are photos from under my microscope:
Opened, removed bearings, no clean
Purple is B, black is A,
I’ll update as clean and measure etc
Cleaned purple:
I think I see the issue. There is a bunch of machining debris in the seats, perhaps that’s why they cracked as well, the debris pressed into and split the plastic. It also looks like the outer ring part cut at an inward angle, making an edge that’s cutting the string. I’m gonna clean and examine the rest, and use some tools to deburr and smooth out that knife edge situation.
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Yeah, that inner radius on the lip around thw bearing is sharp. It shouldn’t be.
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I received my red A grade plasm today. It cut the stock string in less than a day of play. I noticed the radius was sharp. However, this yoyo is so much fun, it’s pretty much worth sacrificing a string a day lol
Love the feel. Wonder if I can use some sand paper to smooth it down?
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Use some denim see if that works first.
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5 micron sandpaper alone did nothing, I had to scrape/ manually bevel the edge with the back of a jewlers file, and then smooth it over with the sandpaper
And here is some 220 to compare
I don’t think that would be controlled enough, however
Finished product still plays great!
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If anyone would like me to deburr theirs, DM, we can work something out.
The patients survived the operation with no lasting complications expected.
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I love the ingenuity of this group of folks. Thankfully my red a grade seems to not cut string so I’m happy. Haven’t messed with the b grades yet
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As I was doing my barbaric scraping and sanding I was literally thinking to myself “Kris is gonna have one of these on a lathe tomorrow” lmao
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When does @pyrotechnic NOT have something on the lathe?
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Tell that to this stack of butterfly’s that I need to mod up
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